Fungus turns ants into zombies

Photo Credit: Dr. David Hughes

Some parasite species have evolved mechanisms to alter their hosts’ mind and control its actions, often co-opting a pre-existing behaviour to its benefits. Although not truly undead in a classical definition of “zombie”, worker ants of the tribe Camponotini (Formicinae: Formicidae) have been found to be under the control of a fungus (Ophiocordyceps unilateralis ) which leaves them no other choice but to follow its commands. Carpenter ants mostly nest high in the canopy of tropical forests in Africa, Australia, Brazil and Thailand. When workers trek down to the forest floor to forage, the fungus attaches itself to them and uses enzymes to break down their exoskeleton to enter the body. Once infected, the fungus uses as-yet unidentified chemicals to direct the ant to leave its hive and take it to a place with the optimal height from the ground, prevalent temperature, humidity and orientation of the leaves, where the ant bites in the underside of a leave and dies. The fungus carries on to grow after the ants’ death, producing a long stem that protrudes from the ant’s head, shooting spores out, while at the same time preserving and reinforcing the ants’ exoskeleton to protect itself. Due to the destructive nature of the fungus which is capable of destroying entire colonies, ants have evolved an ability to detect infected members and will carry away diseased ants in order to contain the exposure to fungal spores. The research of Dr. David Hughes and his colleagues is available online on PLoS ONE.

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